CA2172923A1 - Protective compositions for reducing chemical attacks on plastics - Google Patents

Abstract

There is provided a composition and a polymer film which resists the blistering action of polymer foam blowing agents upon plastics such as styrene-based polymers. The polymer film provides a suitable barrier in refrigeration applications where a high impact polystyrene (HIPS) is particularly susceptible to chemical attack from polyurethane halogenated blowing agents. There is also provided a composite made of a thermoplastic synthetic resin sheet such as HIPS, the polymer film, a polymer foam, and an outer wall element. The polymer film is a mixture of at least three polymers and copolymers: a polyolefin, a copolymer derived from monomers comprising an ethylenically unsaturated aliphatic or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group, and a synthetic block copolymer.

Description

- 2 1 72q23 Docket No. 3756 PROTECI IVE COMPOSITIONS FOR REDUCING
CHEMICAL Al~ACKS ON PLASTICS

BACKGROUND OF THE INVENTION

1. Field of the Lnvention This invention relates to a polymer film used to protect plastics from attack by various chemical agents. More specifically, this invenbon relates to a composition resistant to attack from chemical agents and the polymer film thereof, com~.;si,~g a mixture of three polymers: a polyolefin; a copolymer derived from an ethylenically unsaburated aliphabc or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group; and a styrenic block copolymer.
2. Description of the Background A typical refrigerator appliance cabinet consists of an outer metal cabinet, an inner plasbic liner, typically ABS (acrylonibrile-butadiene-styrene), or HIl~S
(high impact polystyrene), and an insulating polymer foam core, typically polyurethane foam. Blowing agents for the polymer foam are trapped within the cells of the foam. In the past, CFC-11 was usually employed commercially as the 2 1 72q23 -blowing agent. Due to the Montreal protocol, substitutes for CFC-11 and other "hard" halogenated hydrocarbons must be found. Proposed substitutes for CFC-11 are halogenated hydrocarbons that contain at least one hydrogen atom, also known as "soft" CFCs, which have an ozone depletion potential much less than that of CFC-11.
Some of the common blowing agent substitutes currently proposed for insulation-type foams used in refrigeration appliance cabinets are 1,1-dichloro-1-fluoroethane (HCFC-141b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), and 1,1,1,2-tetrafluoroethane (HFC-134a). While the blowing agents are trapped within the cells of the foam, many different kinds of ~-ICFCs diffuse out from cell walls and contact the inner plastic liner of the refrigerator leading to a chemical attack on the liner, which can cause blistering, catastrophic cracks, crazing, and loss of impact properties, as well as stress whitening and/or dissolution.
Blowing agents such as HCFC-141b and HCFC-123 appear to be more chemically agg~ssive than CFC-11 in attacking the inner plastic liner.
Several prol,osals have been made to protect the inner plastic liner from attack by polymer foam blowing agents. For example, U.S. Patent No. 5,227,245 proposes the use of a protective polymer film (barrier) consisting essentially of a thermoplastic polyester resin which is a homo- or copolymer adduct of an _ aromatic dicarboxylic acid in an active hydrogen-containing material. However, this polyester resin copolymer has poor compatibility with styrenic resins; thus, the protective polymer film lacks the desired regrind capability. During the manufacture of appliance cabinets, a thermoplastic synthetic resin sheet, usually made of polystyrene compound, is either co-extruded with or laminated to a barrier layer to make an inner liner, which is trimmed of excess liner material.
The resulting trimmed scrap material containing the protective polymer film is often incorporated into the virgin thermoplastic synthetic resin sheet material.
To successfully recycle the trim or scrap, the protective polymer film composition should be compatible with the thermoplastic synthebc resin sheet composition.
Other compositions proposed as tayers between the foam and the thermoplastic synthetic resin sheets can be found in U.S. Patent No. 4,707,401, which suggests using a bi-layer film, including an inner film containing a copolymer of ethylene and vinyl acetate and an outer film containing a copolymer of ethylene and acrylic acid. The purpose of the outer film, however, was to improve the adhesion between the polyurethane foam and the outer film, while the inner film effectively provides a stress relief layer with the inner synthetic therrnoplastic resin sheet U.S. Patent No. 5,118,174 proposes using both a protective polymer film to prevent diffusion of the insulation foam - 2 1 72q23 blowing agents to the liner sheet, and an adhesive film layer to firmly bond the outer wall of the cabinet to the laminated protective polymer Rlm layer. The proposed composition of the protective polymer film (barrier) was EVOH, saran, nylon, PET, PDT, etc. U.S. Patent No. 5,221,136 proposed adding a protective polymer material to a thermoplastic synthetic resin sheet where the protective polymer (barrier) material was made of a polymer or copolymer of e~hylene or propylene containing 0 to 40 percent of a block copolymer rubber. The block copolymer rubber was optionally functionalized with maleic anhydride, maleic acid, or admixtures thereof in order to maximize the adhesion of the core material to the plol~:live polymer (barrier) material.
It would be desirable to find a composition which exhibits good resistance against attacks by polymer foam blowing agents on thermoplastic synthetic resin sheet It would also be desirable that this same composition is both thermoformable and recyclable.

3. Summary of the Invention There is now provided a composiffon and a polymer film thereof which protects therrnoplastics from chemical attacks by various polymer foam blowing agents. The composition and the polymer film are made of a blend or mixture of polymers and copolymers comprising:

a) a polyolefin, b) a copolymer derived from monomers comprising an ethylenically unsaturated aliphaffc or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic group, and c) a styren;c block copolymer.
The composibon containing the mixture of at least three polymers and copolymers is most preferably made of a mixture of high density polyethylene, a copolymer of ethylene-methacrylic acid, and a synthetic block copolymer rubber such as slylelle-butadiene.
This polymer film composibon can be extruded into a polymer film sheet laminated to or co-exb~uded with a thermoplasbc synthetic resin sheet to make a thermoformable inner liner. The thermoformable inner liner is thermoformed, trimmed, and nested in a spaced relationship within an outer wall element, after which a polymer foam is injected to the space between the inner liner and the outer wall element.
There is also provided a composite, sequentially made of:
i) a thermoplastic synthetic resin sheet, ii) a polymer film, iii) a polymer foam, and, - 21 72~23 iv) an outer wall element Further, there is provided a method of making a thermoformable inner liner sheet comprising:
(A) co-extruding a thermoplastic synthetic resin composibon with a polymer film composition to produce a liner comprising a thermoplastic synthetic resin sheet bonded to a potymer film, or (B) laminating a thermoplasffc synthetic resin sheet to a polymer film, said polymer film and polymer film composition comprising:
(1) a polyolefin;
(2) a copolymer derived from monomers comprising an ethylenically unsaturated aliphaffc or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group; and, (3) a styrenic block copolymer.

4. Description of the Drawings Figure 1 is a schematic drawing of a refrigerator cabinet Figure 2 is a schematic drawing of a thermoformed inner liner.
Figure 3 is a cross-section of a composite made of the inner liner, the polymer foam, and an outer wall element.

5. Detailed Description of the Invention While the invention will be described below with reference to a refrigerator cabinet, it should be understood that the polymer film can be used in other applications where it is desirable to protect a plastic from chemical attack.
The refrigerator cabinet of Figure 1 includes a cabinet and is defined by an outer wall element 1, a thermoformed inner liner wall 2, and a body of foamed-in-place polymer foam insulation 3 between the thermoformed inner liner and the outer wall elemen~ In one popular non-limiting design, the cabinet may define a freezer space 4 and above-freezing refrigeration space 5.
Inner liner wall 2 is thermoformed into the desired configuration as shown in Figure 2. Lnner liner wall 2 is a thermoformed product of the liner sheet 6, one embodiment of which is illustrated in l~igure 3. After being thermoformed into the desired configuration, the inner liner wall 2 is disposed into the outer wall element 1 in a nested spaced relationship for introduction of the polymer foam insulation by conventional foaming-in-place operaffon.
Usually, the outer wall element 1 and the inner liner wall 2 are joined physically by mating of joints. The polymer film of the invention is substantially chemically inert to halogenated hydrocarbons used as blowing agents in polymer foam production. During polymer foam in situ production, in one embodiment of the invention~ the surface of the polymer film is conffguous to and bonds with the foam. However, it is not essential that the polymer film of the invention be contiguous to the foam. In Fi~ure 3, the polymer film is illustrated as Numeral 8.
In Figwe 3, there is also provided a thermoplastic synthetic resin sheet 7, which is preferably in contact with and bonded to polymer film 8. Opffonally, there may be also prov;ded a gloss cap 9, which provides for a pleasingly aesthetic appearance on the inside of the refrigerator cabinet. Thus, in one embodiment of the invention, proceeding sequentially from the innermost to the outermost part of a refrigerator cabinet, there is provided a composite having a:
i) a thermoplastic synthetic resin sheet 7, ii) a polymer fitm 8, iii) a polymer foam 3, and, iv) an outer wall element 1.
The polymer film 8 and the thermoplastic synthetic resin sheet 7 together comprise a thermoformed inner liner 2, which was made from a thermoformable inner liner sheet 6. In another embodiment of the invention, there is also provided a composite and a thermoformable inner liner sheet 6 having a gloss cap 9. There may also be provided optional layers in between any of the layers -1, 3, 8, 7, and 9. For example, there could be provided a thermal sbess release layer or adhesive layer.
In one embodiment that is depicted in ~igure 3 where the optional gloss cap 9 is present, the gloss cap 9 will comprise from 0.5 to 10 weight percent of the thermoformable inner liner sheet 6. The thermoplastic synthebc resin sheet 7 comprises at least 50 weight percent of the thermoformable inner liner sheet 6.
The polymer film 8 comprises from 4 to 50 weight percent of the thermoformable inner liner sheet 6.
The above~escribed layers can be at any thickness desired. In one embodiment of the invenbon, the polymer film 8 thickness ranges from 0.001 to 0.050 inches; the thermoplastic synthebc resin sheet 7 thickness ranges from 0.015 to 0.30 inches; and the opbional gloss cap 9 thickness can range from 0.001 to 0.010 inches in thickness. The polymer foam 3 thickness is usually from 1 to 3 inches.
Turning to the composibon of the individual layers, the polymer film 8 will be described Hrst. The composibon of the polymer film comprises a mixture of at least three polymers and copolymers:
a) a polyolefin, b) a copolymer derived from monomers comprising an ethylenically unsalllldted aliphatic or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic group, and c) a styrenic block copolymer.
The polyolefin of the polymer film composition includes homo-polymers or copolymers of ethylene, propylene, or butylene. Examples include poly~ro~lene, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HVPE) (melt index of 1 to 10 and density of 0.935 to 0.970), high molecular weight-high density polyethylene (melt index of 0.05 to 1.0 and density of 0.935 to 0.970), and ethylene vinyl alcohols. As used herein, the phrase "high density polyethylene" is meant to encompass high density polyethylene having all melt indices ranging from 0.05 to 10 and densities of 0.935 to 0.970.
HDPE materials can be made by polymerizing ethylene using so-called Ziegler-Natta coordination catalysts to provide linear (non-branched), narrow molecular weight distribution HDPEs or the Phillips process to produce broader molecular weight distributions. LDPE materials can be made by polymerizing ethylene using f~radical catalysts under high pressures and high temperatures to provided branched polyethylenes (densities = 0.910 to 0.934 gms/cc), The 2 1 ~2923 LLDPE materials can be prepared from ethylene and minor amounts of alpha, beta-ethylenically unsaturated C3 to Cl2 alkenes under Ziegler-Natta conditions to provide essentially linear low density polyethylenes but with alkyl side chains from the a-olefin components (densities = 0.88 to 0.935 gms/cc). Plefe...2d within 1~is polyethylene group are all the high density polyethylenes as described above.
Examples of HDPEs include those commercially available under the names QUANTUM LM-6187 and LT-6194-69 (melt index of 1.2), HDPEs from Quantum of Cincinnati, Ohio; SOLVAY A 60-70-162 (M.I. of 0.7), F 621 S (M.I. of 1), J 60-500~147 (M.I. of 6), T60-500-119 (M.I. of 6), T50-200-01 (M.I. of 1.7), A60-70-119 (M.I. of 0.7), 660-24-144 (M.I. of 0.25) HDPEs commercially available from Solvay; Mobil HMA034 (M.I. of 5), and NCX-013 (M.I. of 0.7); Chevron 9659 (M.I.
of 1) HDPE; and Phillips EHM 6006 (M.I. of 0.7).
The a) polyolefin may optionally be modified by funcffonalizing a polyolefin with an unsaturated carboxylic acid or its functional derivative or another vinyl functional group-containing monomer. For example, a polyethylene or any other polyolefin can be functionaliæd by grafting onto the olefin polymer backbone compounds such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and ascorbic acid, the acid and anhydrides thereof, acid amides, epoxy group-containing compounds, hydroxyethyl group-containing esters, and metal acrylate sa1ts. Such functionalized polyolefins can improve adhesion of the foam insulation to the polymer film and the polymer film to the thermoplastic synthetic resin sheet The copolymer b) u~sed in the polymer film composition is derived from at least two monomers, one of which is an unsaturated aliphahc or alicyclic hydrocarbon, and the other cont~ining a vinyl group and a carboxylic acid group. The ethylenically unsaturated aliphatic or alicyclic hydrocarbon monomer preferably has only one double bond in the case of the aliphatic hydrocarbons and only two double bonds in the case of alicyclic hydrocarbons.
Examples of the hydrocarbon monomers include the monomers used to make the polyolefins mentioned above, such as ethylene, propylene, butylene, and the copolymers thereof. The p,~el~l,ed hydrocarbon monomer is ethylene.
Any compound containing both a vinyl group and a carboxylic acid group is suitable as the other monomer compound used to make the b) copolymer. Examples of such compounds include, but are not limited to, those within the structural formula:

R O

C~12 = (Cn) - C - OH

wherein Rl, R2, and R3 are independently hydrogen, Cl - C4 alkyl group, a subsfftuted or unsubsbtuted aryl group, or a substituted or unsubstituted aralkyl group; and wherein n is an integer from 0 to 8. Preferably, Rl is hydrogen or a methyl group, and n is 0. Thus the monomer preferably comprises methacrylic acid or acrylic acid; and, more preferably, it comprises methacrylic acid.
The amount of the monomer compound units containing the vinyl and carboxylic acid groups is an amount effecbve to improve the blister resistance of a polymer film made in the absence of the copolymer, such as with only the polyolefin and the styrenic block copolymer or only the polyolefin, styrenic block copolymer, and a poly~lylel-e compound. Examples of suitable amounts range from 4 weight percent to 20 weight percent We have found that amounts of 9 to 12 weight percent, based on the weight of the copolymer, are quite effective in improving the resistance of the polymer film to blistering of a thermoplasbc.

However, any amount of the monomer compound can be used and optimiæd with a view toward minimizing costs and maximizing blister resistance.
Examples of some commercially available copolymers are NUCREI, 1202 HC, 31001, 0407, 0902, and 0903 available from E.I. duPont de Nemours in Wilmington, Delaware.
The b) copolymer is manufactured by copolymerizing the individual monomers one with the other to make a random (heteric) or a block copolymer.
The hydrocarbon monomer and the monomer compound containing the vinyl group and carboxylic acid groups, once polymerized, formed the backbone chain of the copolymer. Thus, the hydrocarbon monomer copolymeriæs through its point of ethylenic unsaturabon with the ethylenic unsaturation present on the vinyl group of the monomer compound.
The third compound of the polymer film composition is a styrenic block copolymer. Suitable styrenic block copolymers will generally be synthebc block copolymer rubbers. Illusbrative examples include styrene-butadiene diblock;
styrene-ethylene-propylene diblock copolymer; styrene-ethylene/butylene-styrene triblock, and star block copolymers. Each of these synthebc block copolymers rubbers can opbonally be functionaliæd with maleic anhydride, maleic acid, acrylic acid, methacrylic acid, fumaric acid, itaconic acid, acid amides, epoxy groups containing compounds such as glycidyl acrylate, g1ycidyl acrylate and glycidyl methacrylate, hydroxyethyl group containing esters such as 2-hydroxyethyl methacrylate and polyethylene glycol monoacrylate, and metal salts such as sodium acrylate, sodium methacrylate, and zinc acrylate, and admixtures thereof, or combinaffons of any of the above. Funcbonalizing the rubber copolymer may assist in improving adhesion of the polymer film to the foam.
Preferred styrenic block copolymers are Stereon 840A, commercially available from Firestone Tire and Rubber Company; Finaclear 520, commercially available from Fina of Houston, Texas; Styrolux 684D, a star block styrenic butadiene b10ck copolymer, Styrolux 2686 and 2689, which are sytrene-butadiene block copolymers, each commercially available from BASF Corporaffon; and Kraton 1101D and G19OlX, commercially available from Shell Oil Company.
The polymer film composition, in one embodiment of the invenffon, contains 35 to 90 weight percent of the a) polyolefin; greater thfln 2.5 weight percent to less than 30 weight percent of the b) copolymer; and from 5 to 25 weight percent of the c) styrenic block copolymer.
Preferably, this embodiment contains from 40 to 85 weight percent of the a) polyolefin; from 5 to 20 weight percent of the b) copolymer; and from 10 to 20 -weight percent of the c) styrenic block copolymer. While amounts greater than 30 weight percent of the b) copolymer can be used in the polymer film, we have found that synergisffc blister resistance results can be obtained by employing only from greater than 2.5 weight percent to less than 30 weight percent of the copolymer in the polymer film composiffon. The synergies observed in increased resistance to blistering of a thermoplastic syntheffc resin sheet are further explained in more detail in the working examples below.
The polymer film may optionally contain other polymers or copolymers beside the three polymers and copolymers menffoned above. For example, a fourth polymer of a different kind of polyethylene or a high impact styrenic polymer or copolymer can be used. A suitable example of a high impact poly~ly~ene would be ES5350, marketed by BASF Corporation.
The polystyrene is preferably high molecular weight polymer, having a weight average molecular weight greater than about 150,000 grams per mole.
The polymer film can be prepared by compounding the individual polymer components in, for example, an extruder, twin screw extruder, FCM, or a Banberry mixer in amounts co..~onding to the desired weight percentage of the components in the polymer film. The individual polymers and copolymers are melted and extruded through a die, then cooled and cut into pellets for processing in subsequent sheet or film operations.
The optional additional high impact polystyrene polymer added to the polymer film composition may be a rubber-modified polystyrene, a well-known material that is a poly~lylene modified by an elastomer such as polybutadiene or a styrene-butadiene polymer. This material is described, for example, in Modern Plastics Encyclopedia, McGraw-Hill, p. 72 (1983-1984). The rubber-modified poly~ly~e~e used in the thermoplastic synthebc resin sheet or as the opbonal additional ingredient in the polymer film can be manufactured by several different methods. The rubber-modified polystyrene may be what is commonly known as high impact polyslylene prepared by polymerizing styrene monomer in the presence of a rubber polymer to form a high impact polyslylene having a morphology wherein rubber particles are dispersed in a polystyrene mabrix, each of the rubber particles comprising polystyrene occlusions agglomerated within the particle and surrounded by a rubber phased interstices. The rubber parbcles are typically 1 to 5 microns in siæ. In another method, styrene monomer may be polymerized in the presence of a synthetic block copolymer rubber such as styrene-butadiene to form a core-shell morphology wherein a polystyrene core is encapsulated by a rubber shell dispersed in a polystyrene matrix. Another method of making a rubber-modified polystyrene is to melt blend a polystyrene polymer with a block copolymer of styrene-butadiene to form small particles ranging from about 0.05 to 0.15 microns in size dispersed as domains in a poly~lyr~ne matrix.
There is also provided an environmental stress crack resistance HIPS
prepared by polymerizing styrene monomer in the presence of a butadiene polymer under certain reaction conditions well known to those of ordinary skill in the art to yield rubber particles ranging from 3 to 30 microns in size.
The amount of high impact polyslyle"e, if used, usually ranges from 10 weight percent to 40 weight percent based on the weight of the polymer film composition.
The thermoplastic synthetic resin sheet 7 can be made of a high impact poly~ly~ e as described above or an acrylonitrile-butadiene-styrene (ABS) copolymer. The high impact poly~lyl~ne, as described above, can optionally be prepared by polymerizing styrene monomer in the presence of rubber polymer.
The ABS copolymer can also optionally be prepared in the ~l~sence of rubber polymer. The amount of rubber in the HIPS or ABS can range from 5 to 35, preferably 5 to 20, usually from 5 to 15, weight percent in the form of particles.
The rubber particles in the HIPS generally have weight average diameters of at least 2 microns, and preferably at least 5 microns, and generally up to 10 microns. When the styrenic block copolymer particles are one (1) micron or less as described in U.S. Patent No. 4,513,120, incorporated herein by reference, high gloss polystyrene (medium impact) is produced.
The optional gloss cap layer 9 can be disposed on the show surface of the thermoplastic resin sheet and is comprised of a medium impact high gloss poly~lylene.
The thermoformable inner liner sheet 6 can be prepared by a co-extrusion technique or a lamination technique. Techniques for applying the film by lamination or co-extrusion with a thermoplastic synthetic resin sheet are well known to those skilled in the art of producing composite materials. Such techniques for the application of film are disclosed in, for example, U.S. Patent No. 3,960,631; 4,005,919; 4,707,401; and 4,196,950, all incorporated herein by reference. In a co-extrusion technique, the thermoplastic synthetic resin composition is co-extruded with a polymer film composition through a sheet die and onto cooling rolls to form a thermoformable inner liner slleet having a layer of thermoplastic synthetic resin sheet heat bonded to the polymer film. Those of ordinary skill in the art will readily appreciate the many co-extrusion techniques available for the manufacture of such an inner liner sheet For example, one such technique involves separately feeding the polymer film composition and the thermoplastic resin sheet composition through a Dow feedblock or through a Welex feedblock. Alternaffvely, the individual materials may be separately fed into a multi-manifold die. In a lamination technique, a thermoplastic synthetic resin sheet material may be extruded, conveyed to pressure rollers, at which point a roll of the polymer film may be unwound and laminated to the thermoplastic synthetic resin sheet through the rollers. The pressure of the rollers and the heat of the extrusion keeping the resin sheet in a softened state provide the means for bonding. Alternatively, instead of lamination, the surfaces of the polymer film and the thermoplastic synthetic resin sheet may be treated ele~llosL~tically to promote the adhesion of the polymer film to the sheet The thermoformable inner liner sheet 6 is then thermoformed into a thermoformed inner liner sheet structure which fits into the desired outer wall element Thermoforming techniques are well known in the art and generally involve a hot drawing process. Examples of therrnoforming techniques are the male billow thermoforming technique and the female billow plug assist technique. The thermoformed inner liner sheet is then trimmed and assembled into the outer wall element in a nested, spaced relationship so as to allow a gap between the inner liner and the outer wall element for the in-situ foaming of the -insulation material. The polymer foam is injected or poured into the gap to form an insulation barrier for a refrigeration unit Thus, there is provided a composite which has the following layers in sequence:
i) a thermoplastic synthetic resin sheet, ii) a polymer film, iii) a polymer foam, and, iv) an outer wall element Suitable polymer foams are those foams that are foamed in place or foams that are laminated to or attached to the outer cabinet wall and the inner liner.
For example, there may be provided a thermoplastic polymer foam such as a polyethylene, a polypropylene, or a polystyrene foam. However, it is plere..æd that the polymer foam comprises a thermosetting polymer, such as a polyisocyanate-based foam, more preferably the polyurethane and/or polyisocyanurate foams. These foams are pr~re.læd because they are fine-celled, closed-celled, dimensionally stable, and can be foamed in place. The polyisocyanate-based foams can be prepared by mixing under reaction conditions an organic polyisocyanate with a polyol composition, the polyol composition including such ingredients such as a polyol having at least two isocyanate reactive hydrogens, a blowing agent, catalyst, and optionally surfactants.
Turning to the ingredients in the polyol composition, there is provided a polyol having at least two isocyanate reactive hydrogens. Preferably, polyhydroxyl compounds having a functionality of 2 to 8, more preferably 3 to 8, and an average hydroxyl number of 150 to 850, more preferably 350 to 800 are examples of polyols. Polyols having hydroxyl numbers outside this range may be used, but it is ~l~r~ d that the average hydroxyl number for the total amount of polyols used fall within the range of 150 to 850.
Examples of polyols include polythioether polyols, polyester amides and polyacetals containing hydroxyl groups, aliphatic polycarbonates containing hydroxyl groups, amine terminated polyoxyalkylene polyethers, and preferably, polyester polyols, polyoxyalkylene polyether polyols, and graft dispersion polyols. In addition, mixtures of at least two of the aforesaid polyols can be used as long as the combination has an average hydroxyl number in the aforesaid range.
The term "polyester polyol" as used in this specification and claims includes any minor amounts of unreacted polyol remaining after the preparation of the polyester polyol and/or unesterified polyol (e.g., glycol) added after the ._ preparation of the polyester polyol. The polyester polyol can include up to about 40 weight percent free glycol.
The polyester polyols advantageously have an average functionality of about 1.8 to 8, preferably about 1.8 to 5, and more preferably about 2 to 3. Their hydroxyl number values generally fall within a range of about 15 to 750, preferably about 30 to 550, and more pre~erably ahout 150 to 500, and their free glycol content generally is from about 0 to 40, preferably from 2 to 30, and more preferably from 2 to 15 weight percent of the total polyester polyol component.
Suitable polyester polyols can be produced, for example, from organic dicarboxylic acids with 2 to 12 carbons, including aromatic and aliphatic acids, and multivalent alcohols, preferably diols, with 2 to 12 carbons, preferably 2 to 6 carbons.
Examples of suitable polyester polyols are those derived from PET scrap and available under the designation Chardol 170, 336A, 560, 570, 571 and 572 from Chardonol and Freol 30-2150 from Freeman Chemical. Examples of suitable DMT derived polyester polyols are Terate(~) 202, 203, 204, 254, 2541, and 254A polyols, which are available from Cape Industries. Phthalic anhydride derived po]yester polyols aré commercially available under the designation Pluracol~ polyol 9118 from BASF Corporation, and Stepanol P~2002, 1~2402, 2 1 72~23 -P~2502A, PS 2502, PS 2522, PS 2852, 1~2852E, 1~2552, and 1~3152 from Stepan Company.
Polyoxyalkylene polyether polyols, which can be obtained by known methods, are also ~ e,l~d for use as the polyhydroxyl compounds~ For example, polyether polyols can be produced by anionic polymerization with alkali hydroxides such as sodium hydroxide or potassium hydroxide or alkali alcoholates, such as sodium methylate, sodium ethylate, or potassium ethylate or potassium isopropylate as catalysts and with the addition of at least one initiator molecule containing 2 to 8, preferably 3 to 8, reactive hydrogens or by cationic polymerization with Lewis acids such as antimony pentachloride, boron trifluoride etherate, etc., or bleaching earth as catalysts from one or more alkylene oxides with 2 to 4 carbons in the alkylene radical. Any suitable alkylene oxide may be used such as 1,3-propylene oxide, 1,2- and 2,3-butylene oxide, amylene oxides, slylelle oxide, and preferably ethylene oxide and 1,2-propylene oxide and mixtures of these oxides. The polyalkylene polyether polyols may be prepared from other starting materials such as tetrahydrofuran and alkylene oxide-tetrahydrofuran mixtures; epihalohydrins such as epichlorohydrin; as well as aralkylene oxides such as styrene oxide. The polyalkylene polyether polyols may have either primary or secondary hydroxyl groups. Included among the 21 72~23 polyether polyols are polyoxyethylene glycol, polyoxypropylene glycol,polyoxybutylene glycol, polytetramethylene glycol, block copolymers, for example, combinabons of polyoxypropylene and polyoxyethylene glycols, poly-1,2-oxybutylene and polyoxyethylene glycols, poly-~,4-tetramethylene and polyoxyethylene glycols, and copolymer glycols prepared from blends or sequential addition of two or more alkylene oxides. The polyalkylene polyether polyols may be prepared by any known process such as, for example, the process disclosed by Wurtz in 1859 and Encyclopedia of Chemical Technolo~y, Vol. 7, pp. 257-262, published by Interscience Publishers, Inc. (1951) or in U.S. Pat No.
1,922,459. Polyethers which are ~ e.,~d include the alkylene oxide addition products of polyhydric alcohols such as ethylene glycol, propylene glycol, di~ o~/lene glycol, trimethylene glycol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, hydroquinone, resorcinol glycerol, glycerine, 1,1,1-trimethylol-propane, 1,1,1-trimethylolethane, pentaerythritol, 1,2,6-hexanetriol, a-methyl glucoside, sucrose, and sorbitol. Also included within the term "polyhydric alcohol" are compounds derived from phenol such as 2,2-bis(4-hydroxyphenyl)-propane, commonly known as Bisphenol A.
Suitable organic amine starffng materials include aliphatic and cycloaliphatic amines and mixtures thereof, having at least one primary amino group, ~ r~lnbly two or more primary amino groups, and most preferable are the diamines. Specific non-limibng examples of aliphabc amines include monoamines having 1 to 12, preferably 1 to 6 carbon atoms, such as methylamine, ethylamine, butylamine, hexylamine, octylamine, decylamine and dodecylamine; aliphabc diamines such as 1,2-diaminoethane, propylene diamine, 1,4-diaminobutane, 1,6-diaminohexane, 2,2~imethyl-,3-propanediamine, 2-methyl-1,5-pentadiamine, 2,5-dimethyl-2,5-hexanediamine, and 4-aminomethyloctan~1,8-diamine, and amino acid-based polyamines such as lysine methyl ester, Iysine aminoethyl ester and cysbne dimethyl ester;
cycloaliphatic monoamines of 5 to 12, preferably of 5 to 8, carbon atoms in the cycloalkyl radical, such as cyclohexylamine and cyclo-octylamine and preferably cycloaliphatic diamines of 6 to 13 carbon atoms, such as cyclohexylenediamine, 4,4'-, 4,2'-, and 2,2'-diaminocyclohexylmethane and mixtures thereof; aromatic monoamines of 6 to 18 carbon atoms, such as aniline, benzylamine, toluidine and naphthylamine and preferably aromatic diamines of 6 to 15 carbon atoms, such as phenylenediamine, naphthylenediamine, fluorenediamine, diphenyldiamine, anthracenediamine, and preferably 2,4- and 2,6-toluenediamine and 4,4'-, 2,4'-, and 2,2'~iaminodiphenylmethane, and aromabc polyamines such as 2,4,6-triaminotoluene, mixtures of polyphenyl-polymethylene-polyamines, and mixtures of diaminidiphenylmethanes and polypllenyl-polymethylene-polyamines. P,erel .ed are ethylenediamine, propylenediamine, decanediamine, 4,4'-diaminophenylmethane, 4,4'-diaminocyclohexylmethane, and toluenediamine.
Suitable initiator molecules also include alkanolamines such as ethanolamine, diethanolamine, N-methyl- and N-ethylethanolamine, N-methyl-and N-ethyldiethanolamine and triethanolamine plus ammonia.
Also suitable as the polyol are polymer modified polyols, in particular, the so-called graft polyols. Graft polyols are well known to the art and are prepared by the in situ polymerization of one or more vinyl monomers, preferably acrylonitrile and styrene, in the presence of a polyether or polyester polyol, particularly polyols containing a minor amount of natural or induced unsaturation. Methods of preparing such graft polyols may be found in columns 1-5 and in the Examples of U.S. Patent No. 3,652,639; in columns 1-6 and the Examples of U.S. Patent No. 3,823,201; particularly in columns 2-8 and the Examples of U. S. Patent No. 4,690,956; and in U.S. Patent No. 4,524,157; all of which patents are herein incorporated by reference.
Non-graft polymer modified polyols are also l~refe,led, for example, those prepared by the reaction of a polyisocyanate with an alkanolamine in the presence of a polyol as taught by U.S. Patents 4,293,470; 4,296,213; and 4,374,209;
dispersions of polyisocyanurates containing pendant urea groups as taught by U.S. Patent 4,386,167; and polyisocyanurate dispersions also containing biuret linkages as taught by U.S. Patent 4,359,541. Other polymer modified polyols may be prepared by the in situ size reducbon of polymers until the parbcle size is less than 20mm, preferably less than 10mm.
The blowing agents which can be used may be divided into the chemically active blowing agents which chemically react with the isocyanate or with other formulation ingredients to release a gas for foaming, and the physically active blowing agents which are gaseous at the exotherm foaming temperatures or less without the necessity for chemically reacbng with the foam ingredients to provide a blowing gas. Included with the meaning of physically acbve blowing agents are those gases which are thermally unstable and decompose at elevated temperatures.
Examples of chemically active blowing agents are ~re~e.enbally those which react with the isocyanate to liberate gas, such as CO2. Suitable chemically acbve blowing agents include, but are not limited to, water, mono- and polycarboxylic acids having a molecular weight of from 46 to 300, salts of these acids, and tertiary alcohols.

Water is ~l~re.~l~tially used as a co-blowing agent. Water reacts with the organic isocyanate to liberate CO2 gas which is the actual blowing agent However, since water consumes isocyanate groups, an equivalent molar excess of isocyanate must be used to make up for the consumed isocyanates.
Phys;cally active blowing agents are those which boil at the exotherm foaming temperature or less, preferably at 50C or less. The most ~rer~.led physically active btowing agents are those which have an ozone depletion potential of 0.05 or less. Examples of physically active blowing agents are the volatile non-halogenated hydrocarbons having two to seven carbon atoms such as alkanes, alkenes, cycloalkanes having up to 6 carbon atoms, dialkyl ethers, cycloalkylene ethers and ketones; hydrochlorofluorocarbons (HCE-Cs);
hydrofluorocarbons (HFCs); perfluorinated hydrocarbons (HFCs); fluorinated ethers (HFCs); and decomposition products.
Examples of volatile non-halogenated hydrocarbons include linear or branched alkanes, e.g. butane, isobutane, 2,3 dimethylbutAne, n- and isopentane and technicat-grade pentane mixtures, n- and isohexanes, n- and isoheptanes, n-and isooctanes, n- and isononanes, n- and isodecanes, n- and isoundecanes, and n- and isododecanes. Furthermore, specific examples of alkenes are 1-pentene, 2-methylbutene, 3-methylbutene, and 1-hexene; of cycloalkanes are cyclobutAne, preferably cyclopentane, cyclohexane or mixtures thereof; specific examples of linear or cyclic ethers are dimethyl ether, diethyl ether, methyl ethyl ether, vinyl mefflyl ether, vinyl ethyl ether, divinyl ether, tetrahydrofuran and furan; and specific examples of ketones are acetone, methyl ethyl ketone and cyclopentanone. P-ef~ tiat alkanes are cyclopentane, n- and isopentane, n-hexane, and mixtures thereof.
Any hydrochlorofluorocarbon blowing agent may be used in the present invention. Preferred hydrochlorofluorocarbon blowing agents include 1-chloro-1,2-difluoroethane; 1-chloro-2,2{1ifluoroethane (142a); 1-chloro-1,1-difluoroethane (142b); 1,1-dichloro-1-fluoroethane (141b); 1-chloro-1,1,2-trifluoroethane; 1-chloro-1,2,2-trifluoroethane; 1,1-dichloro-1,2~ifluoroethane; 1-chloro-1,1,2,2-tetrafluoroethane (124a); 1-chloro-1,2,2,2-tetrafluoroethane (124);
1,1-dichloro-1,2,2-trifluoroethane; 1,1-dichloro-2,2,2-trifluoroethane (123); and 1,2~ichloro-1,1,2-trifluoroethane (123a); monochlorodifluoromethane (HCFC-22); 1-chloro-2,2,2-trifluoroethane (HCFC-133a); gem-chlorofluoroethylene (R-1131a); chloroheptafluoropropane (HCFC-217); chlorodifluoroethylene (HCFC-1122); and trans-chlorofluoroethylene (HCFC-1131). The most l,iefe.læd hydrochlorofluorocarbon blowing agent is 1,1-dichloro-1-fluoroethane (HCFC-141b).

Suitable hydrofluorocarbons, perfluorinated hydrocarbons, and fluorinated ethers include difluoromethane (HFC-32); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1-difluoroethane (HFC-152a);
1,2-difluoroethane (HFC-142), trifluoromethane; heptafluoropropane; 1,1,1-trifluoroethane; 1,1,2-trifluoroethane; 1,1,1,2r2-pentafluoropropane; 1,1,1,3-tetrafluo~ o~ ane; 1,1,2,3,3-pentafluoropropane; 1 ,1,1,3,3-pentafluoro-n-butane;
hexafluorocyclopropane (C-216); octafluorocyclobutane (C-318);
perfluorotetrahydrofuran; perfluoroalkyl tetrahydrofurans; perfluorofuran;
perfluoro-propane,-butane, -cyclobutane, -pentane, -cyclopentane, and -hexane, ~yclohexane,-heptane, and -octane; perfluorodiethyl ether; perfluorodipropyl ether; and perfluoroethyl propyl ether.
Decomposiffon type physically acffve blowing agents which release a gas through thermal decomposiffon include pecan flour, amine/carbon dioxide complexes, and alkyl alkanoate compounds, especially methyl and ethyl formates.
The total and relative amounts of blowing agents will depend upon the desired foam density, the type of hydrocarbon, and the amount and type of additional blowing agents employed. Polyurethane foam densiffes typical for rigid polyulet~ane insulation applications range from free rise densiffes of 0.5 to - 2172q23 10 pcf, p,~.ably from 1.2 to 3.5 pcf. The amount by weight of all blowing agents is generally, based on 100 pbw of the polyols having at least two isocyanate reactive hydrogens, from 0.05 to 45 pbw.
Catalysts may be employed which greatly accelerate the reacbon of the compounds containing hydroxyl groups and with the modified or unmodified polyisocyanates. Examples of suitable compounds are cure catalysts which also funcbon to shorten tack time, promote green sbrength, and prevent foam shrinkage. Suitable cure catalysts are organometallic catalysts, preferably organobn catalysts, although it is possible to employ metals such as lead, titanium, copper, mercury, cobalt, nickel, iron, vanadium, antimony, and manganese. Suitable organometallic catalysts, exemplified here by tin as tlle metal, are ~ sented by the formula: R~n[X-Rt-y2, wherein R is a Cl-Cs alkyl or aryl group, Rl is a Co C18 methylene group optionally substituted or branched with a Cl C4 alkyl group, Y is hydrogen or an hydroxyl group, preferably hydrogen, X is methylene, an -S-, an-SR2COO-, -SOOC-, an -0~, or an OOC-group wherein R2 is a Cl{4 alkyl, n is a or 2, provided that Rl is Co only when X
is a methylene group. Specific examples are bn (II) acetate, bn (II) octanoate, bn (II) ethylhexanoate and tin (II) laurate; and dialkyl (1~C) tin (IV) salts of organic carboxylic acids having 1-32 carbon atoms, preferably 1-20 carbon atoms, e.g., diethylffn diacetate, dibutylffn diacetate, dibutyltin diacetate, dibutylffn dilaurate, dibuty]bn maleate, dihexyltin diacetate, and dioctyltin diacetate.
Other suitable organoffn catalysts are organotin alkoxides and mono or polyalkyl (1 8C) tin (IV) salts of inorganic compounds such as butylbn trichloride, dimethyl- and diethyl- and dibutyl- and dioctyl- and diphenyl- tin oxide, dibutylffn dibutoxide, di(2-ethylhexyl) tin oxide, dibutyltin dichloride, and dioctyltin dioxide. Pl~rell~d, however, are tin catalysts with ffn-sulfur bonds which are resistant to hydrolysis, such as dialkyl (1-20C) tin dimercaptides, including dlmethyl-, dibutyl-, and dioctyl- ffn dimercaptides.
Tertiary amines also promote urethane linkage formation, and include triethylamine, 3-methoxypropyldimethylamine, triethylenediamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl- and N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine or -hexanediamine, N,N,N'-trimethyl isopropyl propylenediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1-methyl~-dimethylaminoethylpiperazine, 1,2-dimethylimidazole, 1-azabicylo[3.3.0]octane and preferably 1,4-diazabicylo[2.2.2]octane, and alkanolamine compounds, such as triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine and dimethylethanolamine.
To prepare the polyisocyanurate (PIR) and PUR-PIR foams by the process according to the invention, a polyisocyanurate catalyst is employed. Suitable polyisocyanurate catalysts are alkali salts, for example, sodium salts, preferably potassium salts and ammonium salts, of organic carboxylic acids, expediently having from 1 to 8 carbon atoms, preferably 1 or 2 carbon atoms, for example, the salts of formic acid, acetic acid, propionic acid, or octanoic acid, and tris(dialkylaminoethyl)-, tris(dimethylamninopropyl)-, tris(dimethylaminobutyl)- and the corresponding tris(diethylaminoalkyl)-s-hexahydrotriazines. However, (trimethyl-2-hydroxypropyl)ammonium formate, (trimethyl-2-hydroxypropyl)ammonium octanoate, potassium acetate, potassium formate and tris(diemthylaminopropyl)-s-hexahydrotriazine are polyisocyanurate catalysts which are generally used. The suitable polyisocyanurate catalyst is usually used in an amount of from 1 to 10 parts by weight, preferably form 1.5 to 8 parts by weight, based on 100 parts by weight of the total amount of polyols.
Examples of suitable surfactants are compounds which serve to support homogenization of the starting materials and may also regulate the cell structure of the plastics. Specific examples are salts of sulfonic acids, e.g., alkali metal salts or ammonium salts of fatty acids such as oleic or stearic acid, of dodecylbenæne-or dinaphthylmethanedisulfonic acid, and ricinoleic acid; foam shbilizers, such as siloxane-oxyalkylene copolymers and other organopolysiloxanes, oxyethylated alkyl-phenols, oxyethylated fatty alcohols, paraffin oils, castor oil esters, ricinoleic acid esters, Turkey red oil and groundnut oil, and cell regulators, such as paraffins, fatty alcohols, and dimethylpolysiloxanes. The surfactants are usually used in amounts of 0.01 to 5 parts by weight, based on 100 parts by weight of the polyol component Examples of suitable flameproofing agents are tricresyl phosphate, tris(2-chloroethyl) phosphate, tris(2-chloropropyl) phosphate, and tris(2,3-dibromopropyl) phosphate.
In addibon to the above-menboned halogen-subsbtuted phosphates, it is also possible to use inorganic or organic flameproofing agents, such as red phosphorus, aluminum oxide hydrate, anbmony trioxide, arsenic oxide, ammonium polyphosphate (Exolit~) and calcium sulfate, expandable graphite or cyanuric acid derivatives, e.g., melamine, or mixtures of two or more flameproofing agents, e.g., ammonium polyphosphates and melamine, and, if desired, corn starch, or ammonium polyphosphate, melamine, and expandable graphite and/or, if desired, aromatic polyesters, in order to flameproof the polyisocyanate polyaddition products. Jn general, from 2 to 50 parts by weight, preferably from 5 to 25 parts by weight, of said flameprooRng agents may be used per 100 parts by weight of the polyols.
Optional flame retardant compounds are tetrakis(2-chloroethyl) ethylene phosphonate, pentabromodiphenyl oxide, b^is(1,3~ichloropropyl) phosphate, tris(beta-chloroethyl) phosphate, molybdenum trioxide, ammonium molybdate, ammonium phosphate, pentabromodiphenyloxide, tricresyl phosphate, 2,3-dibromopropanol, hexabromocyclododecane, dibromoethyldi-bromocyclohexane, tris(2,3-dibromopropyl)phosphate, tris(beta-chloroplopyl)phosphate, and melamine.
The organic polyisocyanates include all essentially known aliphatic, cycloaliphatic, araliphaffc and preferably aromabc mulffvalent isocyanates.
Specific examples include: alkylene diisocyanates with 4 to 12 carbons in the alkylene radical such as 1,12-dodecane diisocyanate, 2-ethyl-1,4-tetramethylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate, 1,4-tetramethylene diisocyanate and preferably 1,6-hexamethylene diisocyanate; cycloaliphatic diisocyanates such as 1,3- and 1,4-cyclohexane diisocyanate as well as any mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-2 1 72q23 isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4- and 2,6-hexahydrotoluene diisocyanate as well as the corresponding isomeric mixtures, 4,4'- 2,2'-, and 2,4'-dicyclohexylmethane diisocyanate as well as the co..~onding isomeric mixtures and preferably aromatic diisocyanates and polyisocyanates such as 2,4- and 2,~toluene diisocyanate and the co,les~onding isomeric mixtures 4,4'-, 2,4'-, and 2,2'-diphenylmethane diisocyanate and the col,es~onding isomeric mixtures, mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates and polyphenylenepolymethylene polyisocyanates (polymeric MDI), as well as mixtures of polymeric Ml)I and toluene diisocyanates. The organic di- and polyisocyanates can be used individually or in the form of mixtures.
Frequently, so-called modified multivalent isocyanates, i.e., products obtained by the partial chemical reaction of organic diisocyanates and/or polyisocyanates are used. Examples include diisocyanates and/or polyisocyanates containing ester groups, urea groups, biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups, and/or urethane groups.
Specific examples include organic, preferably aromatic, polyisocyanates containing urethane groups and having an NCO content of 33.6 to 15 weight percent, ~l~felably 31 to 21 weight percent, based on the total weight, e.g., with low molecular weight diols, triols, dialkylene glycols, trialkylene glycols, or polyoxyalkylene glycols with a molecular weight of up to 1500; modified 4,4'^
diphenylmethane diisocyanate or 2,4- and 2,6-toluene diisocyanate, where examples of di- and polyoxyalkylene glycols that may be used individually or as mixtures include diethylene glycol, dipropylene glycol, polyoxyethylene glycol, polyoxyl,lo~ylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, and polyoxypropylene polyoxyethylene glycols or -triols. Prepolymers containing NCO groups with an NCO content of 25 to 9 weight percent, preferably 21 to 14 weight percent, based on the total weight and produced from the polyester polyols and/or preferably polyether polyols described ~xlow; 4,4'-diphenylmethane diisocyanate, mixtures of 2,4'- and 4,4'-diphenylmethane diisocyanate, 2,4,- and/or 2,6-toluene diisocyanates or polymeric MDI are also suitable. Furthermore, liquid polyisocyanates containing carbodiimide groups having an NCO content of 33.6 to 15 weight percent, preferably 31 to 21 weight percent, based on the total weightf have also proven suitable, e.g., based on 4,4'-and 2,4'- and/or 2,2'-diphenylmethane diisocyanate and/or 2,4'- and/or 2,6-toluene diisocyanate. The modified polyisocyanates may optionally be mixed logetl~er or mixed with unmodified organic polyisocyanates such as 2,4'- and 4,4'-diphenylmethane diisocyanate, polymeric MDI~ 2,4'- and/or 2,6-toluene diisocyanate.
The foams produced contained in the closed celled sbructure residual amounts of the blowing agent. The polyisocyanate-based foams are formed in situ by foaming in a high pressure mixhead equipped to a nozzle for inbroducing the foam and foaming components into the cavity formed by the nesbng of the outer wall element and the inner liner.

In this example, the synergistic effect of an e~ylene-methacrylic acid copolymer on the blister time will be demonstrated. Sheets of the polymer film were tested for their effectiveness against chemical attack upon a high impact polystyrene sheet. Protecbve polymer fitm composibons described in Tahle 1 below were prepared by compounding the individual ingredients in a single screw extruder at 200C. Sbrands exiting from a circular die were cooled in a water bath, then chopped into pellets. Several of those pellets were placed between two polyester films and pressed in a hydraulic press between platens heated to 350F to make Rlms of 0.002 inch thickness. The polyester Rlms were removed from the test Rlm. In a similar manner, approximately 0.03 inch thick sheets were prepared from pellets of ES 7100 HIPS. The test film and the ES 7100 sheet were placed together between the polyester films and the hydraulic press again was used to produce a 0.03 inch thick laminate. Circular test specimens of 16 mm diameter were cut form the laminate using a cork borer.
A screw top glass bottle (70 mm high, 20 mm diameter) was partly filled with approximately 6 cm3 of HCFC 141b. The circular test specimen was placed on the top of the bottle, with the test film side exposed to the HCFC 141b. A
chemically resistant plastic bottle top with a 12 mm diameter hole was screwed onto the bottle to seal in the HCFC 141b. The effect of the HCFC 141b diffusion through the test film was monitored for chemical attack on the HIPS ES 7100 layer. The ffme was recorded when blistering of the HIPS ES 7100 layer occurred, and the results are set forth in Table 1 below. The lower time noted in the range indicates a ffme when no blistering was apparent, and the upper time in the range was a ffme when blistering was evident During the testing, the bottles were kept at 35C.
Below is a des..;plion of all the ingredients used and set forth in Table 1:
Quantum LM 6187 is a high density polyethylene commercially available from Quantum.
tereon 840a is a styrene-butadiene block rubber copolymer commercially available from Firestone.

2 1 72q23 UCREL 0903 is an ethylene-methacrylic acid copolymer containing 9 weight percent of methacrylic acid based on the weight of the copolymer, commercially available from E.I. DuPont de Nemours.
inaclear 520 is a slyl.2ne-butadiene diblock copolymer obtained from Fina.
ES 5350 is a high impact poly~ly.ene commercially available from BASF Corporaffon.

BLISl~ER

7 65 0 15 20 0 44~5 High density polyethylene used alone provides good protection aga;nst a chemical attack on the HIPS layer as shown by the high blister time of 48-50 hours in Sample 1. However, the pure high density polyethylene film is commercially unsuitable as a ylol~liv~ film because it has no adhesion to the HIPS thermoplastic resin sheet layer. Therefore, a component such as a block styrene/butadiene copolymer must be added in commercial applications to improve adhesion. As shown in Sample 2, however, addition of only 15 percent of a styren~butadiene block copolymer dramaticatly decreased the blister time from 48-50 hours to ~16 hours.
The 100 percent composition of NUCREL in Sample 3, which is an ethylene-methacrylic acid copolymer, also provided good resistance against chemical attack on the HIPS thermoplastic layer as shown by the 30-32 hours to blister ffme. An ethylene copolymer of acrylic acid or metllacrylic acid also provides polyurethane foam adhesion. Pure NUCREL, however, does not provide as good a blister resistance as a high density polyethylene film (Sample 1). And, as expected, addition of block styrene/butadiene copolymer, as shown in Samples 4 and 5, also reduced the time to blister in the NUCREL ethylene-methacrylic acid copolymer Rlm.

2 ~ 72923 One would expect that combining the composition of Sample 2, which contained rubber and a high density polyethylene (8-16 hours), with the composition of Samples 4 or 5 containing rubber and NUCREL (20-24 hours), would provide a final composition having hours to blister somewhere between ~16 hours and 20-24 hours. Quite unexpectedly, however, the combination had the opposite effect and synelgislically increased tlle hours to blister as shown in Samples 6-8. Combining the ethylene-methaclylic acid copolymer, the high density polyethylene, and the styrene-butadiene block copolymers in Sample 6 increased the hours to blister above and beyond what the individual bi-component compositions could produce by themselves, keeping the amount of block styrene-butadiene copolymer at the same weight percent. As shown by Samples 7 and 8, either a decrease in the amount of ethylene-methacrylic acid copolymer to 20 percent or a slight decrease in the amount of styrene-butadiene block copolymer yielded a composition having an hours-to-blister nearly approaching that of pure high density polyethylene, all the while obta;ning the benefits of enhanced adhesion by incorporation of the styrene-butadiene block copolymer.
As was previously mentioned above, the polymer film composition may optionally contain a high impact polystyrene polymer. Samples 9-13 show the effect of the copolymer on polymer film compositions containing high impact poly~ly~ e. A blend of high impact polystyrene, high density polyethylene, and a styrenic block copolymer does not provide suitable protective acbon against chemical attack on the high impact polystyrene thermoplastic synthebc resin sheet layer as shown in the low hours to blister of Samples 9, 11, and 12.
However, addition of the ethylene-methacrylic acid copolymer improved the hours to blister even in compositions containing high impact polyslylene. This is also surprising s;nce the relabve proportion of lligh density polyethylene, which by itself would provide good blister resistance, was reduced in those compositions containing the ethylene-methacrylic acid copolymer. Yet, the blister resistance was nevertheless increased.

Sheets of the polymer film were tested for their effectiveness against chemical attack upon a high impact polyslylel~e sheet. The same method of manufacturing the laminate of sheets and the test procedures as noted in Example 1 above was used in this example.
The following ingredients were used to make the polymer film:
Nucrel 0903 is an ethylene-methacrylic acid copolymer.

Finaclear 520 is a styrene-butadiene diblock copolymer.
Quantum LM 6187 is a high density polyethylene.
ES 5350 is a high impact polystyrene.

2 1 72~23 SAMPLE NUCREL FINACLE QUANTUM ES 5350 35 C 141b HRS

4 2.5 15 82.5 0 8-16 13 2.5 10 62.5 25 8-16 18 30 10 35 25 ~6-18 The results of Sample 1, where no polymer film was present, showed that the HIPS ES 7100 layer blistered within a matter of only two to three hours. In Sample 2, a pure high density polyethylene film was used as a protecbve layer;
and blisk~,ing occurred in 50-52 hours. However, as noted above, protecffve films containing only high density polyethylene are not commercially useful.
When some styrenic block copolymer was incorporated into the high densily polyethylene film, as in Sample 3, the hours to blister were reduced dramatically to 16-18 hours. However, incorporation of the styrenic block copolymer particles was necessary to promote adhesion between the polymer film and the HIPS
thermoplastic synthetic resin sheet Incorporabon of a small amount of the ethylene-methacrylic acid copolymer into the polymer film, as shown in Sample 4 in an amount of 2.5 weight percent based upon the weight of the polymer film, resulted in further decreased blister bme, which at first glance made it appear that the copolymer would generally negabvely impact the protective acbon of the polymer film.
Surprisingly, as shown in Sample 5, further addition of the ethylene-methacrylic acid copolymer into the polymer film composition dramabcally increased the blister time from ~16 hours to 44-45 hours. Therefore, an amount of ethylene-methacrylic acid copolymer above 2.5 weight percent is effecbve to bynelgislically increase the blister time. This dramatic increase in blister ffme continued unffl the amount of the ethylen~methacrylic acic1 copolymer reached 30 weight percent based upon the weight of the polymer film as shown in Sample 9, at which point the blister time reduced to 26-28 hours. Nevertheless, the blister time in Samples 9-11 using an amount of copolymer greater than 30 weight percent were still higher than in Samples 1, 3, and 4, where the amount of the copolymer was either O or 2.5. Therefore, there is no upper limit on the amount of ethylene-meth~crylic acid copolymer one may add to the polymer fitm composition in order to obtain an improvement in the blister time. For cost considerations, however, and to obtain the optimum synergistic effects, it is ~l~rell~d that the amount of copolymer range from greater than 2.5 weight percent to less than 30 weight percent, based upon the weight of the polymer film composition.
Samples 12-19 differ from Samples 1-11 in that the former contain an additional ingredient in the polymer film composition, a high impact polyslylelle. A comparison of Sample 12 with Sample 13 shows that the addition of the high impact poly~lylene somewhat reduced the blister time. Again, no observable improvement was evident when only 2.5 weight percent of the ethylene-methacrylic acid copolymer was added to the polymer film 2 1 72~23 composition as shown in Sample 13. However, the blister time doubled upon addition of 5 weight percent of the NUCREL copolymer as shown in Sample 14, co"linued to increase up to 10 weight percent, and stabilized through 20 weight percent and then decreased again at 30 weight percent and beyond. Thus, even with the addition of the high impact polystyrene which has a detrimental effect on the l"ot~live acbon of the polymer film, the addition of NUCREL also dramatically improved the blister time of this composition.

In this example, the effect of different kinds of ethylene-vinyl acid copolymers were tested on the polymer film's resistance to blistering of the adjacent HIPS layer. Using the same procedure as described above in Examples 1 and 2, the hours to blister were tested for different compositions listed below in Table 3. To a polymer film composition comprising 65 weight percent of Quantum LM-6187 (a high density polyethylene) and 15 weight percent Finaclear 520 (a slylene-butadiene block copolymer mbber) were added 20 weight percent of different kinds of NUCREL ethylene-vinyl acid copolymers.
The composition of the different kinds of NUCREL copolymers are as follows:
NUCREL 1202HC contains 12 weight percent methacry-lic acid having a melt index of 2;

NUCREL 31001 contains 10 weight percent acrylic acid having a melt index of 1.3;
NUCREL 0407 contains 4 weight percent methaclylic acid having a melt index of 7;
NUCREL 0902 contains 9 weight percent methacrylic acid having a melt index of 2;
NUCREL 0903 contains 9 weight percent methacrylic acid having a melt index of 3.

2 1 72~23 SAMPLE NUCREL NUCREL NUCREL NUCREL NUCREL HOURS

BLISTER
AT 35C.
141b 2 -- 20 2~30 .

The results of the e~ ents ~.rolmed above show that while methacrylic acid ~lrulmed much better than acrylic acid, acrylic acid still provided a measure of l~sislal~ce to the bLl~ g action of 141b. Furthermore, while only 4 weight ~l~ent of &e methacrylic acid based on the weight of the ethylene-m~tll~rylic acid copolymer continued to provide a measure of resistance against the Blisl~ g action of 141b, more optimum amounts range from greater than 4 weight percent as shown in Samples lj 4, and 5.
An important consideration when manufacturing any new composition as a ok~liv~ polymer film is its regrind/recycle capability. Whether using the co-extrusion or the lamination process, there is produced a thermoformable inner liner sheet comprising a thermoplasbc syntheffc resin sheet bonded to a protective film. The sheet is then thermoformed, and the excess is trimmed. This b~im, rather than being discarded, is recycled back into the extruder used to make the thermoplasffc synthetic resin sheet. The thermoplastic synthebc resin sheet is typically made of high impact polystyrene. Since the scrap and brim contains both a sheet of high impact polystyrene and the protecbve film made up of the polyolefin, the copolymer, and styrenic block copolymer, recycling back the scrap and trim into the virgin high impact polystyrene material used to make the synthebc resin sheet now introduces at least three other polymer compositions into the virgin HIPS. As a result, it is possible that the mechanical ~ro~llies of the thermoplasbc synthetic resin sheet may be affected by the addition of the trim and scrap. In particular, we have found that a virgin composition of 95 weight percent of ES 7100 and 5 weight percent of ES 7860, both high impact polystyrenes commercially available from BASF Corporation, extruded through a Brabender 3/4-inch single screw exbruder and injecbon molded on a 28-ton Arburg, having a 200C barrel temperature set at an eight (8) second injection time, produced a thermoplastic synthetic resin 0.125 inch thick plaque having a Gardner impact of about 200 inch-lb. However, when 10 weight 2 1 ~2923 ent of a polymer film composiffon comprising, each based upon the weight of the polymer film composition, 20 weight percent NUCREL 0903, 15 weight percent FINACLEAR 520, and 65 weight percent QUANlUM LM 6187 was added to 85 weight percent ES 7100 and 5 weight percent ES 7860, the Gardner impact of the mixture was reduced to 110 inch-lb. Therefore, adding scrap or trim to a virgin high impact poly~lyl~he mixture such that the overall combination would contain ~0 weight percent of the polymer film composibon reduces the Gardner impact strength.
We have found, however, that the Gardner impact strength can be increased by further adding to the virgin high impact polystyrene mixture containing the polymer film composition, a small amount of styrenic block copolymer, preferably a styrenic-butadiene block copolymer. For example, adding only one (1) weight percent of FINACLEAR 520 styrene-butadiene block copolymer rubber to the mixture of virgin high impact poly~ly~ e and 10 weight percent of polymer film composiffon increased the Gardner impact strength of the thermoplastic syntheffc resin sheet to 290 inch/lb., wllich is far beyond the impact strength of the virgin high impact poly~lyl e ne alone.
Thus, a further feature of the invenLion comprises a recycling process comprising me1t blending a high impact poly~lyrene composition with -thermoformable inner liner material, said inner liner material comprising a layer of thertnoplasffc synthetic resin sheet material and a polymer film, and combining with the melt blend an efr~live amount of a synthetic block copolymer rubber. An err~ live amount would be that considered sufficient to raise the Gardner impact strength of a sheet of material produced from said ingredients to the desired level, preferably the Gardner impact strength of 180 inch-lbs. or greater, more preferably 200 inch-lbs., most preferably 250 inch-lbs.
or greater. Examples of suitable amounts of styrenic block copolymers range from 0.5 to 2 weight percent, based on the weigtlt of the polymer film material in the melt blend and the styrenic block copolymer.
In this process, the styrenic block copolymer is separately added to the virgin high impact polyslyl~l)e and to scrap and trim, rather than adding additional amounts of synthetic block copolymer rubber to the polymer composition. We have found that increasing the amount of styrenic block copolymer in the polymer film composition has a deleterious effect upon the blister resistance of the polymer film composition. Therefore, it is yr~r~lnble to separately add the styrenic block copolymer to the virgin high impact poly~yl~ne and the scrap and trim, and extrude them together to form a thermoplasbc syntheffc resin sheet material which can be bonded to a polymer fflm composition either by c~extrusion or by laminabon.

Claims (60)

1. A composition resistant to the blistering action of polymer foam blowing agents comprising:
(a) a polyolefin;
(b) a copolymer derived from monomers comprising an ethylenically unsaturated aliphatic or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group; and, (c) a styrenic block copolymer.

2. The composition of claim 1, said polyolefin comprising high density polyethylene.

3. The composition of claim 1, said hydrocarbon monomer comprising a C2-C4 aliphatic monomer.

4. The composition of claim 3, said hydrocarbon monomer comprising ethylene.

5. The composition of claim 4, said monomer compound comprising acrylic acid or methacrylic acid.

6. The composition of claim 5, said monomer compound comprising methacrylic acid.

7. The composition of claim 1, wherein said styrenic block copolymer comprises a block copolymer derived from at least two different monomers comprising styrene, ethylene, butylene, or conjugated double bonded compounds, each optionally functionalized with maleic acid or maleic anhydride.

8. The composition of claim 7, said styrenic block copolymer comprises a diblock of styrene-butadiene.

9. The composition of claim 8, said polyolefin comprising high density polyethylene, and said copolymer comprising an ethylene-methacrylic acid copolymer or an ethylene-acrylic acid copolymer.

10. The composition of claim 9, said copolymer comprising an ethylene-methacrylic acid copolymer.

11. The composition of claim 1, comprising (a) 35 weight percent to 90 weight percent of the polyolefin;
(b) greater than 2.5 weight percent to less than 30 weight percent of the copolymer; and, (c) 5 weight percent to 25 weight percent of the styrenic block copolymer, each based on the weight of the composition.

12. The composition of claim 11, comprising (a) 40 weight percent to 85 weight percent of the polyolefin;
(b) 5 weight percent to 20 weight percent of the copolymer; and, (c) 10 weight percent to 20 weight percent of the styrenic block copolymer.

13. The composition of claim 11, wherein said polyolefin comprises high density polyethylene, and said copolymer comprises an ethylene-methacrylic acid or an ethylene-acrylic acid copolymer.

14. The composition of claim 13, wherein said copolymer comprises an ethylene-methacrylic acid copolymer.

15. The composition of claim 13, further comprising high impact polystyrene.

16. The composition of claim 15, wherein the amount of said high impact polystyrene ranges from 10 weight percent to 40 weight percent based on the weight of the composition.

17. A polymer film comprising (a) a polyolefin;
(b) a copolymer derived from monomers comprising an ethylenically unsaturated aliphatic or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group; and, (c) a styrenic block copolymer.

18. The polymer film of claim 17, said polyolefin comprising high density polyethylene.

19. The polymer film of claim 17, said hydrocarbon monomer comprising a C2-C4 aliphatic monomer.

20. The polymer film of claim 19, said hydrocarbon monomer comprising ethylene.

21. The polymer film of claim 20, said monomer compound comprising acrylic acid or methacrylic acid.

22. The polymer film of claim 21, said monomer compound comprising methacrylic acid.

23. The polymer film of claim 17, wherein said styrenic block copolymer comprises a block copolymer derived from at least two different monomers comprising styrene, ethylene, butylene, or conjugated double bonded compounds, each optionally functionalized with maleic acid or maleic anhydride.

24. The polymer film of claim 23, said styrenic block copolymer comprises a diblock of styrene-butadiene.

25. The polymer film of claim 24, said polyolefin comprising high density polyethylene, and said copolymer comprising an ethylene-methacrylic acid copolymer or an ethylene-acrylic acid copolymer.

26. The polymer film of claim 25, said copolymer comprising an ethylene-methacrylic acid copolymer.

27. The polymer film of claim 17, comprising (a) 35 weight percent to 90 weight percent of the polyolefin;
(b) greater than 2.5 weight percent to less than 30 weight percent of the copolymer; and, (c) 5 weight percent to 25 weight percent of the styrenic block copolymer, each based on the weight of the polymer film.

28. The polymer film of claim 27, comprising (a) 40 weight percent to 85 weight percent of the polyolefin;
(b) 5 weight percent to 20 weight percent of the copolymer; and, (c) 10 weight percent to 20 weight percent of the styrenic block copolymer.

29. The polymer film of claim 27, wherein said polyolefin comprises high density polyethylene, and said copolymer comprises an ethylene-methacrylic acid or an ethylene-acrylic acid copolymer.

30. The polymer film of claim 29, wherein said copolymer comprises an ethylene-methacrylic acid copolymer.

31. The polymer film of claim 29, further comprising high impact polystyrene.

32. The polymer film of claim 31, wherein the amount of said high impact polystyrene ranges from 10 weight percent to 40 weight percent based on the weight of the composition.

33. The polymer film of claim 17, wherein the film has a thickness ranging from 0.001 to 0.050 inches.

34. A composite comprising, in sequence:
(i) a thermoplastic synthetic resin sheet, (ii) a polymer film, (iii) a polymer foam, and (iv) an outer wall element, wherein said polymer film comprises (a) a polyolefin;

(b) a copolymer derived from monomers comprising an ethylenically unsaturated aliphatic or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group; and, (c) a styrenic block copolymer.

35. The composite of claim 34, wherein (i) the resin sheet comprises a high impact polystyrene, and (iii) the polymer foam comprises a polyurethane foam blown with a blowing agent comprising a halogenated hydrocarbon.

36. The composite of claim 34, wherein the resin sheet is 0.015 inches to 0.30 inches in thickness, the polymer film is 0.001 inches to 0.05 inches in thickness, and the polymer foam is 1 to 3 inches in thickness.

37. The composite of claim 34, wherein the polymer is film is co-extruded with the resin sheet.

38. The composite of claim 34, further comprising a gloss cap in contact with the side of the resin sheet opposite to the polymer film.

39. The composite of claim 34, said polyolefin comprising high density polyethylene.

40. The composite of claim 34, said hydrocarbon monomer comprising ethylene, and said monomer compound comprising acrylic acid or methacrylic acid.

41. The composite of claim 40, said monomer compound comprising methacrylic acid.

42. The composite of claim 34, said styrenic block copolymer comprises a block copolymer derived from at least two different monomers comprising styrene, ethylene, butylene, or conjugated double bonded compounds, optionally functionalized with maleic acid or maleic anhydride.

43. The composite of claim 42, said styrenic block copolymer comprises a diblock of styrene-butadiene.

44. The composite of claim 43, said polyolefin comprising high density polyethylene, and said copolymer comprising an ethylene-methacrylic acid copolymer.

45. The composite of claim 34, comprising (a) 35 weight percent to 90 weight percent of the polyolefin;
(b) greater than 2.5 weight percent to less than 30 weight percent of the copolymer; and, (c) 5 weight percent to 25 weight percent of the styrenic block copolymer, each based on the weight of the polymer film.

46. The composite of claim 45, wherein said polyolefin comprises high density polyethylene, said copolymer comprises an ethylene-methacrylic acid, and said styrenic block copolymer comprises a synthetic block copolymer.

47. The composite of claim 46, wherein the polymer film further comprises high impact polystyrene.

48. The composite of claim 48, wherein the amount of said high impact polystyrene ranges from 10 weight percent to 40 weight percent based on the weight of the polymer film.

49. A method of making a thermoformable inner liner sheet comprising:
(A) co-extruding a thermoplastic synthetic resin composition with a polymer film composition to produce a liner comprising a thermoplastic synthetic resin sheet bonded to a polymer film, or (B) laminating a thermoplastic synthetic resin sheet to a polymer film, said polymer film and polymer film composition comprising:
(1) a polyolefin;
(2) a copolymer derived from monomers comprising an ethylenically unsaturated aliphatic or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group; and, (3) a styrenic block copolymer.

50. The method of claim 49, comprising melting the individual compositions and separately feeding the individual compositions through a co-extrusion feed block or through a multi-manifold die.

51. The method of claim 49, wherein the liner is thermoformed in a female billow plug assist or a male billow, trimmed, and nested in a spaced relationship inside a wall cabinet, and a polymer foam is injected or poured into the space between the liner and wall cabinet.

52. The method of claim 49, said polyolefin comprising high density polyethylene, said hydrocarbon monomer comprising ethylene, said monomer compound comprising acrylic acid or methacrylic acid, and said styrenic block copolymer comprises a block copolymer derived from at least two different monomers comprising styrene, ethylene, butylene, or conjugated double bonded compounds, optionally functionalized with maleic acid or maleic anhydride.

53. The method of claim 52, said monomer compound comprising methacrylic acid.

54. The method of claim 52, said styrenic block copolymer comprises a diblock of styrene-butadiene.

55. The method of claim 49, said polymer film and polymer film composition comprising (a) 35 weight percent to 90 weight percent of the polyolefin;
(b) greater than 2.5 weight percent to less than 30 weight percent of the copolymer; and, (c) 5 weight percent to 25 weight percent of the styrenic block copolymer, each based on the weight of the composition.

56. The method of claim 55, said polymer film and polymer film composition further comprising high impact polystyrene.

57. A method of recycling comprising:
(a) combining a high impact polystyrene composition with a thermoformable inner liner material, said inner liner comprising a layer of a thermoplastic synthetic resin sheet and a layer of a polymer film;
(b) combining with the a) ingredients an additional amount of a synthetic block copolymer styrenic block copolymer; and, (c) extruding the ingredients to form a thermoplastic synthetic resin sheet containing recycled inner liner material;

wherein said polymer film composition comprises a polyolefin, a copolymer derived from monomers comprising an ethylenically unsaturated aliphatic or alicyclic hydrocarbon monomer and a monomer compound containing a vinyl group and a carboxylic acid group; and, a styrenic block copolymer.

58. The method of claim 57, wherein the amount of said additional synthetic block copolymer rubber is effective to raise the Gardner impact strength of thermoplastic synthetic resin sheet without the added synthetic block copolymer rubbers.

59. The method of claim 58, wherein the Gardner impact strength of the thermoplastic synthetic resin sheet containing recycled inner liner material is 150 inch-lb. or greater at a thickness of 0.125 inches.

60. The method of claim 59, wherein the Gardner impact strength is 200 inch-lb.
or greater at a thickness of 0.125 inches.